How Acanthamoeba polyphaga Mimivirus Changed Virology

Abstract

In 2003, researchers discovered a peculiar virus infecting amoeba. The virus was bigger than any virus found before and much bigger than the smallest bacteria. This virus is Acanthamoeba polyphaga mimivirus, and it set the stage for the discovery of several species that scientists now call giant viruses. The question of what constitutes a living organism creates a lively debate in a room of microbiologists and nobody can seem to come to an agreement on whether viruses should be considered alive.

Giant viruses further muddy the waters of the debate, as they possess features that makes their complexity rival bacteria and some eukaryotes. The discovery has also revived a few hypotheses that center viruses at the base of our evolutionary tree. As smaller bacteria and larger viruses are discovered, microbiologists may need to revisit these questions about what qualifies life and the origin of complex species again, but with mimivirus as their starting point.